The multitude of information that is indicated to a vehicle driver due to the growth in the number of comfort systems such as navigation systems, telecommunication devices, driver-assistance systems as well as warning messages, etc., is increasing steadily. As a result, many vehicles are already provided with so-called multi-function operating devices, which are disposed in the center of the console, in particular. Given such an arrangement, in order to receive the information, the driver is forced to take his eyes away from the traffic. For this reason, at least a portion of the information is preferably displayed in the instrument cluster arranged in the driver's field of view in the driving direction. Under these circumstances the problem arises that only a certain display area in the instrument cluster is available, besides the analog display elements for speed, rotary speed, etc.
New arrangements for instrument clusters, which are able to display a larger variety of information without dispensing with the usual analog display instruments, are therefore under development.
European Published Patent Application No. 0 482 805, for example, describes an instrument cluster in which a first and a second image source are provided. An image-forming illumination of the first image source is reflected to the observer by a planar combination device and two additional mirrors located in the beam path of the reflected light.
The image-forming illumination of the second image source is transmitted by the combining device, and then also reflected to the observer by the two mirrors. The first image source may include a group of electromechanical indicator devices such as for speed, oil pressure, gas level, and display-panel lights such as the turn signal indictor, high beam and emergency indicators. The second image source is arranged as a liquid crystal display to provide alphanumeric information, such as messages, maintenance instructions and settings for the environment. In this instrument cluster, neither of the two image sources is in the driver's direct visual field, so that a purely virtual image is created. Furthermore, in such an instrument cluster, it is difficult to control the parallaxes so as to prevent image distortions, the parallaxes being caused by the different locations of the image sources and the multiple reflections of the image-forming light of the image sources.
Moreover, Japanese Published Patent Application No. 2002-79848 describes an instrument cluster for a motor vehicle having a conventional electromechanical indicator device into whose display image a virtual image of a display device, which is not arranged within the vehicle driver's field of view, is reflected via a concave, semitransparent mirror, which is arranged to pass through the image-forming light of the electromechanical indicator device. However, using this indicator device, it is not possible to overcome the problem of conventional indicator devices, i.e., displaying a greater variety of different information in a rapidly comprehensible manner for the vehicle driver, since space for the reflected image of the display device must be reserved in the electromechanical indicator device.